Abstract
The interaction between aluminium ion (Al) and quinolic acid (L) in acidic aqueous solution was investigated by poten-tiometry and 13C and 27Al NMR spectroscopy. In the 27Al NMR spectra, two peaks were observed at 8 and 15.6 ppm, which were assigned to AlL and AlL2 complexes, respectively. The 13C NMR spectra provide clear evidence that the L acts as a bidentate ligand and that the L coordinates with a nitrogen atom and an oxygen atom of the adjacent carboxylic group to form a chelate complex with a five-membered ring. From a potentiometric study, the formation constants (log β1 and log β2) for the AlL and AlL2 complexes were estimated to be 4.52±0.02 and 7.99±0.05, respectively.
